This controller is for when you have an area that isnt quite accessible by the Robomow when mowing. So if you have a small area behind trees that is difficult for the mower to reach on its own, you can simply move your Robomow to that area by hand and cut the lawn using the controller to direct the machine. This controller is compatible with the Robomow Rc304, Rc306, Rc312, Rs612, Rs622, Rs630. The controller is powered by two AA batteries. Material: Other Material.